Piston type compressor

ABSTRACT

A piston type compressor has a cylinder block, a cylinder bore formed in the cylinder block, a rotary shaft, a piston and a compression chamber formed in the cylinder bore. The piston is received in the cylinder bore and reciprocates in accordance with the rotation of the rotary shaft. The compressor further has a main suction chamber communicable with the compression chamber, a discharge chamber formed annularly so as to surround the main suction chamber, a subsidiary suction chamber formed so as to surround the discharge chamber, partitions formed in the discharge chamber so as to protrude into the discharge chamber and a suction passage formed in each partition so as to interconnect the subsidiary suction chamber and the main suction chamber.

BACKGROUND OF THE INVENTION

The present invention relates to a suction structure in a piston typerefrigerant compressor.

In a piston type compressor with a housing having formed therein adischarge chamber and a suction chamber, wherein refrigerant gas issupplied to the suction chamber from the outer periphery of the housingand discharged from the discharge chamber toward the outer periphery ofthe housing, the suction chamber is disposed on the radially outer sideof the discharge chamber or on the radially inner side of an annulardischarge chamber. A compressor with the suction chamber located on theouter side of the discharge chamber is disclosed in Japanese UtilityModel Application Publication No. 59-105076 and Japanese PatentApplication Publication No. 2000-120532 and a compressor with thesuction chamber located on the inner side of the annular dischargechamber is disclosed in Japanese Patent Application Publication No.7-233783.

In the compressor of the Japanese Utility Model Application PublicationNo. 59-105076, an oil reservoir is formed on the inner side of theannular discharge chamber and the suction chamber and the oil reservoirare connected through a communication passage extending across thedischarge chamber. Lubrication oil separated from the refrigerant gasflowing through the communication passage is reserved in the oilreservoir.

In the compressor wherein the suction chamber is formed in the housinginward of the annular discharge chamber and refrigerant gas is suppliedto the suction chamber from the outer periphery of the housing, it isdesirable that the communication passage through which refrigerant gasis supplied to the suction chamber should be formed so as to extendacross the discharge chamber in view of the need of downsizing thehousing. If the discharge chamber is divided in the circumferentialdirection, discharge pulsation is not sufficiently suppressed.Therefore, it is desirable that the annular discharge chamber should notbe divided by the communication passage, but formed as a single chamber,as disclosed in the Japanese Utility Model Application Publication No.59-105076.

The Japanese Patent Application Publication No. 7-233783 discloses acompressor in which a plurality of ribs are formed in the dischargechamber thereby to form a plurality of small chambers. According to thisPublication, since any two adjacent small chambers are not isolated butcommunicate with each other, the discharge pulsation is effectivelysuppressed. However, the Publication makes no reference to the structureof a suction passage extending across the discharge chamber tocontribute to increasing the suction efficiency.

The present invention is directed to providing a piston type compressorin which refrigerant gas is supplied to a suction chamber from an outerperipheral region of the compressor outward of a discharge chamberlocated outward of the suction chamber, and which reduces the dischargepulsation and improves the suction efficiency.

SUMMARY OF THE INVENTION

A piston type compressor has a cylinder block, a cylinder bore formed inthe cylinder block, a rotary shaft, a piston and a compression chamberformed in the cylinder bore. The piston is received in the cylinder boreand reciprocates in accordance with the rotation of the rotary shaft.The compressor further has a main suction chamber communicable with thecompression chamber, a discharge chamber formed annularly so as tosurround the main suction chamber, a subsidiary suction chamber formedso as to surround the discharge chamber, partitions formed in thedischarge chamber so as to protrude into the discharge chamber and asuction passage formed in each partition so as to interconnect thesubsidiary suction chamber and the main suction chamber.

Other aspects and advantages of the invention will become apparent fromthe following description, taken in conjunction with the accompanyingdrawings, illustrating by way of example the principles of theinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

The features of the present invention that are believed to be novel areset forth with particularity in the appended claims. The inventiontogether with objects and advantages thereof, may best be understood byreference to the following description of the presently preferredembodiments together with the accompanying drawings in which:

FIG. 1 is a longitudinal sectional view of a fixed displacementdouble-headed piston type compressor according to a first preferredembodiment of the present invention;

FIG. 2A is a sectional view taken along the line A-A of FIG. 1;

FIG. 2B is a sectional view taken along the line B-B of FIG. 1;

FIG. 3 is a longitudinal sectional view of a fixed displacementdouble-headed piston rotary valve type compressor according to a secondpreferred embodiment of the present invention;

FIG. 4A is a sectional view taken along the line C-C of FIG. 3; and

FIG. 4B is a sectional view taken along the line D-D of FIG. 3.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following will describe the first preferred embodiment of the fixeddisplacement double-headed piston type compressor according to thepresent invention with reference to FIGS. 1 and 2. The compressor isgenerally designated by numeral 10. The front and rear sides of thecompressor correspond to the left and right sides in the drawing,respectively. The compressor has a housing assembly including a pair offront and rear cylinder blocks 11, 12 and a pair of front and rearhousings 13, 14. The front cylinder block 11 is connected to the rearcylinder block 12. The front and rear housings 13, 14 are connected tothe front and rear cylinder blocks 11, 12, respectively. Thus, the frontand rear cylinder blocks 11, 12 and the front and rear housings 13, 14cooperate to form the housing assembly of the fixed displacementdouble-headed piston type compressor 10.

A rotary shaft 25 is rotatably supported by the front and rear cylinderblocks 11, 12 through front and rear radial bearings 26, 27. A swashplate 28 is secured to the rotary shaft 25. A shaft seal device 35 isinterposed between the front housing 13 and the rotary shaft 25 so as toprevent refrigerant gas from leaking between the outer surface of therotary shaft 25 and the front housing 13.

As shown in FIG. 2A, the front housing 13 has formed therein asubsidiary suction chamber 130 as a part of the suction-pressure regionof the compressor, a main suction chamber 131 as a part of thesuction-pressure region and a discharge chamber 132 as a part of thedischarge-pressure region of the compressor. The main suction chamber131 and the discharge chamber 132 are separated by an annular partitionwall 15A and the annular discharge chamber 132 is formed so as tosurround the main suction chamber 131. The subsidiary suction chamber130 and the discharge chamber 132 are separated by an annular partitionwall 15B and the annular subsidiary suction chamber 130 is formed so asto surround the discharge chamber 132.

As shown in FIG. 1, the front housing 13 has formed therein alubrication passage 134 interconnecting the main suction chamber 131 anda seal chamber 351 having therein the aforementioned shaft seal device35. The lubrication oil flows together with the refrigerant gas from themain suction chamber 131 into the seal chamber 351 through thelubrication passage 134 for lubricating the shaft seal device 35.

The front housing 13 has formed therein a plurality of partitions 33(four partitions in the embodiment as shown in FIG. 2A) protruding fromthe inner wall 133 of the front housing 13 into the discharge chamber132 toward a valve plate 16. The partitions 33 extend from the innerpartition wall 15A to the outer partition wall 15B across the dischargechamber 132.

Each partition 33 has formed therethrough a radial suction passage 331interconnecting the subsidiary suction chamber 130 and the main suctionchamber 131. A valve plate 16, valve forming plates 17, 18 and aretainer forming plate 19 are interposed between the front cylinderblock 11 and the front housing 13. The valve plate 16, the valve formingplate 18 and the retainer forming plate 19 have formed therethrough asuction port 161, and the valve plate 16 and the valve forming plate 17have formed therethrough a discharge port 162, respectively. The valveforming plates 17, 18 have formed therewith a suction valve 171 and adischarge valve 181, respectively. The suction valve 171 and thedischarge valve 181 open and close the suction port 161 and thedischarge port 171, respectively. The retainer forming plate 19 hasformed therewith a retainer 191 for regulating the opening degree of thedischarge valve 181.

The front cylinder block 11, the valve plate 16 and the front housing 13have formed therethrough inlet and outlet passages 111, 112 extending inthe axial direction of the rotary shaft 25. The inlet passage 111communicates with the subsidiary suction chamber 130 and the outletpassage 112 communicates with the discharge chamber 132.

The partitions 33 are located so as to space apart each other along thecircumferential direction of the annular discharge chamber 132.Therefore, the annular discharge chamber 132 is divided into a pluralityof small chambers R1, R2, R3, R4 by the plurality of partitions 33, asshown in FIG. 2A, but these small chambers R1-R4 communicate each otherso as to form a single annular discharge chamber. Each cross-sectionalarea of the discharge chamber 132 where the partition 33 is formedbetween adjacent small chambers is smaller than that of the otherannular part of the discharge chamber 132. Each of the small chambersR3, R4 located far from the outlet passage 112 is provided in one-to-onerelation to its corresponding cylinder bore 29. Similarly, each of thesmall chambers R1, R2 located close to the inlet passage 112 is alsoprovided in one-to-one relation to its corresponding cylinder bore 29.The front outlet passage 112 is connected with only the small chamber R1of the discharge chamber 132. Thus, the refrigerant gas flows throughthe respective small chamber R1, R2, R3 and R4 before reaching the frontoutlet passage 112.

As shown in FIG. 2B, the rear housing 14 has formed therein a subsidiarysuction chamber 140 as a part of the suction-pressure region of thecompressor 10, a main suction chamber 141 also as a part of thesuction-pressure region and a discharge chamber 142 as a part of thedischarge-pressure region. The main suction chamber 141 and thedischarge chamber 142 are separated by an annular partition wall 24A andthe discharge chamber 142 is formed annularly so as to surround the mainsuction chamber 141. The subsidiary suction chamber 140 and thedischarge chamber 142 are separated by an annular partition wall 24B andthe subsidiary suction chamber 140 is formed annularly so as to surroundthe discharge chamber 142.

As shown in FIG. 1, the rear housing 14 has formed therein a pluralityof partitions 34 (four partitions in the embodiment as shown in FIG. 2B)protruding from the inner wall 143 of the rear housing 14 into thedischarge chamber 142 toward a valve plate 20. The partitions 34 extendfrom the inner partition wall 24A to the outer partition wall 24B acrossthe discharge chamber 142.

Each partition 34 has formed therethrough a suction passage 341interconnecting the subsidiary suction chamber 140 and the main suctionchamber 141. As shown in FIG. 1, the valve plate 20, valve formingplates 21, 22 and a retainer forming plate 23 are interposed between therear cylinder block 12 and the rear housing 14. The valve plate 20, thevalve forming plate 22 and the retainer forming plate 23 have formedtherethrough a suction port 201, and the valve plate 20 and the valveforming plate 21 have formed therethrough a discharge port 202. Thevalve forming plates 21, 22 have formed therewith a suction valve 211and a discharge valve 221, respectively. The suction valve 211 and thedischarge valve 221 open and close the suction port 201 and thedischarge port 202, respectively. The retainer forming plate 23 hasformed therewith a retainer 231 for regulating the opening degree of thedischarge valve 221.

The rear cylinder block 12, the valve plate 20 and the rear housing 14have formed therethrough an inlet passage 121 and an outlet passage 122extending in the axial direction of the rotary shaft 25. The inletpassage 121 communicates with the subsidiary suction chamber 140 and theoutlet passage 122 communicates with the discharge chamber 142,respectively.

As shown in FIG. 2B, the annular discharge chamber 142 is separated intoa plurality of small chambers S1, S2, S3, S4 by the partitions 34, butthese small chambers communicate each other so as to form a singleannular discharge chamber. Each of the small chambers S3, S4 located farfrom the outlet passage 122 is provided in one-to-one relation to itscorresponding cylinder bore 30. Similarly, each small chambers S1, S2located close to the inlet passage 122 is also provided in one-to-onerelation to its corresponding cylinder bore 30.

As shown in FIG. 1, the front and rear inlet passages 111, 121 aredistributed from a main passage 123 which is formed in the rear cylinderblock 12 and the front and rear outlet passage 112, 122 are merged intoa joint passage 124 formed in the rear cylinder block 12. The mainpassage 123 communicates with the joint passage 124 through an externalrefrigerant circuit (not shown) of the air conditioning system in whichthe compressor 10 is connected.

The front and rear cylinder blocks 11, 12 have formed therethrough aplurality of pairs of front and rear cylinder bores 29, 30 (fivecylinder bores in the embodiment as shown in FIGS. 2A, 2B) arrangedaround the rotary shaft 25, respectively. Each pair of front and rearcylinder bores 29, 30 receives therein a double-headed piston 31.

The rotational movement of the swash plate 28 rotatable integrally withrotary shaft 25 is transferred to the reciprocal movement of thedouble-headed piston 31 in its corresponding cylinder bores 29, 30through shoes 32 provided in slide contact with the swash plate 28, withthe result that compression chambers 291, 301 are formed in the cylinderbores 29, 30.

When the double-headed piston 31 moves rightward in FIG. 1, therefrigerant gas in the main suction chamber 131 is drawn into thecompression chamber 291 through the suction port 161 while pushing openthe suction valve 171 and, simultaneously, the refrigerant gas in thecompression chamber 301 is discharged into the discharge chamber 142through the discharge port 202 while pushing open the discharge valve221.

On the other hand, when the double-headed piston 31 moves leftward inFIG. 1, the refrigerant gas in the compression chamber 291 is compressedand then discharged into the discharge chamber 132 through the dischargeport 162 while pushing open the discharge valve 181 and, simultaneously,the refrigerant gas in the main suction chamber 141 is drawn into thecompression chamber 301 through the suction port 201 while pushing openthe suction valve 211.

The refrigerant gas discharged into the discharge chambers 132, 142flows out to the external refrigerant circuit through the outletpassages 112, 122 and the joint passage 124, respectively. Therefrigerant gas flowed out to the external refrigerant circuit flowsback into the subsidiary suction chambers 130, 140 through the mainpassage 123 and the inlet passages 111, 121, respectively. Then, therefrigerant gas flows into the main suction chambers 131, 141 throughthe suction passages 331, 341, respectively.

The above-described first embodiment of the present invention offers thefollowing advantageous effects.

-   (1) The refrigerant gas in the discharge chambers 132 and 142 flows    from one small chamber to another R1 through R4 and S1 through S4,    respectively, so that the refrigerant gas is contracted and expanded    repeatedly while flowing through the small chambers, with the result    that the discharge pulsation of refrigerant gas is reduced.    Therefore, the provision of a plurality of partitions 33 and 34    protruding into the discharge chambers 132, 142 so as to separate    the discharge chambers 132, 142 into a plurality of small chambers    R1 through R4 and S1 through S4, respectively, contributes to    reducing the discharge pulsation.

If there is only one partition 33, 34 in the discharge chamber 132, 142,respectively, the frequency of the contraction and expansion of therefrigerant gas is reduced, which is not desirable for the reduction ofthe discharge pulsation. If there is only one partition 33, 34 and henceonly one suction passage 331, 341 in the discharge chamber 132, 142, theamount of the refrigerant gas flowing to the suction ports 161, 201located far from the suction passages 331, 341 is smaller than that ofthe refrigerant gas flowing to the suction ports 161, 201 located closeto the suction passages 331, 341, with the result that the suctionefficiency deteriorates.

The structure of the discharge chamber with a plurality of partitions33, 34 and hence with a plurality of small chambers R1 through R4 eachcorresponding to one cylinder bore 29 contributes to equalizing theamount of the refrigerant gas drawn through the respective suction ports161, 201 thereby to improve the suction efficiency.

-   (2) The inner surfaces of the front and rear housings 13, 14 are    suitable for forming the partitions 33, 34.-   (3) In the double-headed piston type compressor 10, the arrangement    of the discharge chamber 132 surrounding the main suction chamber    131 is advantageous in realizing a simple structure for supplying    lubrication oil in the main suction chambers 131, 141 to the shaft    seal device 35 in that the main suction chamber 131 and the seal    chamber 351 are connected to each other only through the lubrication    passage 134. Therefore, the double-headed piston type compressor 10    with the main suction chambers 131, 141 located radially inward of    the discharge chamber 132, 142, respectively, is advantageous in    lubricating the shaft seal device 35 for the rotary shaft 25.

The following will describe the second embodiment with reference toFIGS. 3 and 4. The same reference numerals denote components or elementssimilar to those of the first embodiment and the detailed descriptionthereof will be omitted. As shown in FIG. 3, the front and rear cylinderblocks 11, 12 of the double-headed piston type compressor 10A haveformed therethrough shaft holes 36, 37 through which the rotary shaft 25extends. The rotary shaft 25 is directly supported by the front and rearcylinder blocks 11, 12 through the inner surfaces of the shaft holes 36,37 which are in contact with the outer surface of the rotary shaft 25.The outer surface of the rotary shaft 25 in contact with the shaft holes36, 37 provide sealing surfaces 251, 252, respectively.

The rotary shaft 25 has formed therethrough an axial passage 38extending in axial direction of the rotary shaft 25. The axial passage38 communicates with the main suction chamber 131 through an inletpassage 135 formed in the front housing 13, so that the refrigerant gasin the main suction chamber 131 can be drawn into the axial passage 38through the inlet passage 135. Since the inlet passage 135 communicateswith the seal chamber 351, the lubrication oil in the main suctionchamber 131 can flow to the seal chamber 351 thereby to lubricate theshaft seal device 35.

The axial passage 38 also communicates with the main suction chamber 141in the rear housing 14, so that the refrigerant gas in the main suctionchamber 141 can flow from the rear end of the rotary shaft 25 into theaxial passage 38. The rotary shaft 25 in the shaft holes 36, 37 areformed with front and rear suction ports 381, 382 of the axial passage38 which are opened to the front and rear seal surfaces 251, 252 of therotary shaft 25, respectively.

As shown in FIGS. 4A, 4B, the front and rear cylinder blocks 11, 12 haveformed therethrough front and rear communication passages 39, 40interconnecting the cylinder bores 29, 30 and the shaft holes 36, 37,respectively. The front and rear suction ports 381, 382 of the axialpassage 38 intermittently communicate with the front and rearcommunication passages 39, 40, respectively, in accordance with therotation of the rotary shaft 25.

When the double-headed piston 31 moves leftward in FIG. 3, the rearsuction port 382 communicates with the rear communication passage 40. Inthis state, the refrigerant gas in the main suction chamber 141 is drawninto the compression chamber 301 in the cylinder bore 30 through theaxial passage 38, the rear suction port 382 and the rear communicationpassage 40.

When the double-headed piston 31 moves rightward in FIG. 3, on the otherhand, the front suction port 381 communicates with the frontcommunication passage 39. In this state, the refrigerant gas in the mainsuction chamber 131 is drawn into the compression chamber 291 in thecylinder bore 29 through the inlet passage 135, the axial passage 38,the front suction port 381 and the front communication passage 39.

Thus, the front and rear seal surfaces 251, 252 of the rotary shaft 25form front and rear rotary valves 41, 42, respectively, which areintegrally formed with the rotary shaft 25. The front suction port 381and the axial passage 38 cooperate to form a supply passage of the frontrotary valve 41 and, similarly, the rear suction port 382 and the axialpassage 38 cooperate to form a supply passage of the rear rotary valve42.

The second embodiment also offers the same advantageous effects as thefirst embodiment. Since the piston type compressor 10A with the rotaryvalves 41, 42 inevitably has the main suction chamber located radiallyinward of the discharge chamber, the present invention may be appliedsuitably to the piston type compressor 10A with the rotary valves 41,42.

The present invention is not limited to the embodiments described above,but it may be modified in various way as exemplified by the followingalternative embodiments. The number of the partitions in the dischargechamber may be two, three or more than five. The present invention maybe applied also to a variable displacement compressor as disclosed inthe Japanese Patent Application Publications No. 7-233783 and No.2000-120532.

The present invention is applicable further to a fixed displacementpiston type compressor with a single-headed piston.

1. A piston type compressor comprising: a cylinder block; a cylinder bore formed in the cylinder block; a rotary shaft; a piston, wherein the piston is received in the cylinder bore and reciprocates in accordance with the rotation of the rotary shaft; a compression chamber formed in the cylinder bore; a main suction chamber communicable with the compression chamber; a discharge chamber formed annularly so as to surround the main suction chamber, the discharge chamber being communicable with the compression chamber; a subsidiary suction chamber formed so as to surround the discharge chamber; partitions formed in the discharge chamber so as to protrude into the discharge chamber; and a suction passage formed in each partition so as to interconnect the subsidiary suction chamber and the main suction chamber.
 2. The piston type compressor according to claim 1, further comprising: a housing connected to the cylinder block, wherein the discharge chamber, the subsidiary suction chamber and the main suction chamber are formed in the housing, and the partition is formed on inner wall of the housing.
 3. The piston type compressor according to claim 1, further comprising: a rotary valve formed in the rotary shaft with an axial passage for supplying refrigerant gas from the main suction chamber to the compression chamber; and a communication passage formed in the cylinder block so as to interconnect the axial passage and the compression chamber.
 4. The piston type compressor according to claim 1, wherein a pair of front and rear cylinder blocks cooperate to form the cylinder block and the cylinder bore is formed in each of the front and rear cylinder blocks, wherein the piston is a double-headed piston, the double-headed piston being received in the front and rear cylinder bores, respectively, wherein a pair of front and rear housings are connected to the pair of front and rear cylinder blocks, respectively, a plurality of partitions with suction passages being formed in the front and rear housings, respectively.
 5. The piston type compressor according to claim 1, further comprising: a plurality of small chambers divided in the discharge chamber by the partitions, wherein the small chambers are connected each other thereby to form the single discharge chamber.
 6. The piston type compressor according to claim 5, further comprising: an outlet passage connecting with one of the plurality of small chambers in the discharge chamber.
 7. The piston type compressor according to claim 5, further comprising: wherein the cross-sectional area of the discharge chamber where the partition is formed between the adjacent small chambers is smaller than that of the other annular parts of the discharge chamber.
 8. The piston type compressor according to claim 1, wherein each of the small chambers is provided in one-to-one relation to its corresponding cylinder bore.
 9. The piston type compressor according to claim 1, further comprising: a seal device interposed between the rotary shaft and the housing so as to prevent leakage of the refrigerant gas; a seal chamber having therein the seal device; and a lubrication passage formed in the housing so as to interconnect the main suction chamber and the seal chamber.
 10. The piston type compressor according to claim 1, wherein the partitions are spaced apart from each other along the circumferential direction of the discharge chamber.
 11. The piston type compressor according to claim 1, wherein the partition extends from the subsidiary suction chamber to the main suction chamber across the discharge chamber. 